1. Field
Example embodiments relate to a ferroelectric capacitor having a three-dimensional structure, a nonvolatile memory device having the same, and a method of fabricating the same.
2. Description of the Related Art
A problem with the fabrication of semiconductor devices may be a side-effect caused by a mutual diffusion of materials. The mutual diffusion of materials may result from the interface characteristics of component materials used in forming a semiconductor device and/or a higher processing temperature in the fabrication of semiconductor devices.
Conventional semiconductor memory devices are being developed (e.g., a ferroelectric random access memory (FRAM) semiconductor memory device, magnetic random access memory (MRAM) and/or a phase change random access memory (PRAM)). There have been efforts to modify the structure of a ferroelectric capacitor in a FRAM into various shapes and structures in order to achieve relatively high integration of the device. During the processing of a conventional ferroelectric capacitor, a concentration of Pb in a PZT layer may be reduced due to a mutual diffusion of Pb of the PZT layer and Si in a layer under the PZT layer.
When the concentration of Pb in the PZT layer is reduced, a crystal structure of the PZT layer may be changed from a perovskite structure to a pyrochlore structure. If the crystal structure is changed, the PZT layer may not have normal polarization characteristics and may not be beneficial as a ferroelectric. Even though the change in the crystal structure is confined to a local region of the PZT layer, the region of the PZT usable as a ferroelectric may be reduced and an effective area of the ferroelectric capacitor may be reduced.